Lens grinding and polishing apparatus



Aug. 23, 1955 L. D. BRONSON LENS GRINDING AND POLISHING APPARATUS 4 Sheets-Sheet 1 Filed Nov- 7. 1952 mm T E w 2 m5 W 5 9 p w 0 l Aug. 23, 1955 1.. D. BRONSON 2,715,803

LENS GRINDING AND POLISHING APPARATUS Filed Nov. 7, 1952 4 Sheets-Sheet 2 I N V EN TOR. LOU/5 0. BRONSON 26 BY JAM flfiqa Aug. 23, 1955 1.. D. BRONSON LENS GRINDING AND POLISHING APPARATUS 4 Sheets-Sheet 3 Filed Nov. 7, 1952 INVEN TOR. LOU/5 0. BRO/VSO/V 4 TTORNE Y Aug. 23, 1955 L. D. BRONSON LENS GRINDING AND POLISHING APPARATUS Fild NOV. 7, 1952 4 Sheets-Sheet 4 JNVENTOR.

LOU/S 0. saw/501v Raj/AM H 7TORNE'Y United States Patent 9 LENS GRINDHVG AND POLISHING APPARATUS Louis D. Bronson, Square, N. Y.

Application November 7, 1952, Serial No. 319,233

1 Claim. (Ci. 51124) This invention relates to lens grinding and polishing apparatus.

The principal object of this invention is the provision of a simple, highly eflicient apparatus for spherical and cylindrical grinding and polishing of lens surfaces. As used in this specification, the term cylindrical" signifies a curved but non-spherical surface, as said term is employed in the optical industry and profession.

Optical grinding and polishing machines may be divided for classification purposes into two categories: Spherical grinding and polishing machines and cylindrical grinding and polishing machines. The conventional spherical grinding and polishing machine is not normally adapted for cylindrical grinding and polishing. Conversely, the conventional cylindrical grinding and polishing machine is not well adapted for spherical grinding and polishing. Consequently, opticians and others in the optical industry find it necessary to procure, maintain and use both a spherical and a cylindrical grinding and polishing machine.

Some efforts have been made to devise a combination machine which would be capable of both types of grinding and polishing and while these efforts have to some extent been successful, the combination machines which these efforts have produced have been overly complicated in their structure and mechanism and cumbersome and faulty in their operation. Consequently, these combination machines have been unnecessarily expensive both to the manufacturer and to the purchaser and user.

The grinding and polishing machine herein claimed is very simple in construction and operation and it consists of relatively few parts which are readily assembled and disassembled for use, replacement, cleaning and other purposes. It occupies relatively little space and its operation is virtually vibrationless. This is in sharp contrast to the combination machines which have thus far been developed, said machines being extremely complicated in construction and operation, occupying an excessive amount of space, and producing violent vibrations in operation.

An important feature of the grinding and polishing apparatus herein described and claimed is the number and direction of the relative movements between the grinding or polishing tool and the work. In a conventional cylindrical grinding and polishing machine, the relative movements are usualy two. The same is true of a conventional spherical grinding and polishing machine. In the combination spherical and cylindrical grinding and polishing machines of the prior art, the relative movements between the tool and the work are normally three. In the present machine there are four. It must be understood that the greater the number of relative movements between the tool and the work, the more efficient the grinding or polishing operation.

In the present machine, the work is mounted on a rotating holder and the tool is mounted on a rotating mandrel. Although the work and the tool rotate simultaneously with each other and at the same angular .or polishing liquid to the work and tool.

Patented Aug. 23, 1955 speed, means is provided for shifting the work relative to the tool into two directions: forwardly and backwardly and also leftwardly and rightwardly. A fourth motion is also forwardly and backwardly of the work relative to the tool, but such movement difiers from the first mentioned forward and backward movement in that it traverses the direction which the latter movement takes as well as the direction which the leftward and rightward movement takes. The fourth motion may therefore be more appropriately described as an angular motion which no other optical grinding and polishing machine now in existence incorporates.

Another important feature of the present invention is the means which it provides for applying the abrasive A force feed of such liquid is provided in the present machine without the use of a pump or other pressure means. More specifically, what is here provided is a rotating bowl which contains the abrasive or polishing liquid, a scoop which is held in a stationary position in said bowl adjacent its inner wall, and a tube which is connected at one end to said scoop and which is positioned at its opposite end adjacent the work and tool. As the bowl rotates, the liquid rotates with it and centrifugal force tends to throw it outwardly and against the inner wall of the bowl. The scoop is positioned to intercept or catch the liquid and to channel it up through the tube and against the work and tool.

Still another important feature is the adjustability of the apparatus herein described and claimed. It is adjustable in every conceivable sense, so as to accommodate a lens of virtualy every size and shape (within the physical space limitations of the apparatus), reference being here made to width and length as well as to thickness. The machine is also adjustable to apply varying degrees of pressure upon the work and the tool. It is also adjustable to compensate for wear, particularly of the stylus which presses the work against the tool. The machine is adjustable so as to provide greater or lesser relative movement between the tool and the work.

Simplicity has been mentioned as one of the important features of this machine. An important aspect of this feature is the fact that all of the important operative parts of the machine, with the sole exception of the pressure stylus, are mounted for rotary movement on a common mandrel. Reference is here made to the bowl which contains the abrasive or polishing liquid, the tool, the work holder and hence the work, and the guide means which guide the movement of the work holder and the work relative to the tool.

Preferred forms of this invention are shown in the accompanying drawing in which;

Fig. 1 is a side view, partly in vertical section, of a lens grinding and polishing machine made in accordance with one form of this invention.

Fig. 2 is a front view of the same machine, its bowl being partly broken away to expose its working parts.

Fig. 3 is a horizontal section on line 33 of Fig. 1.

Fig. 4 is a top view of the bowl, the tool and the work holder, looking in the direction of arrows 4-, 4 of Fig. i.

Fig. 5 is a fragmentary perspective view of the pressure applying means of a machine made in accordance with a second form of this invention.

Fig. 6 is a fragmentary back view thereof.

Fig. 7 is a SL3 view of a lens grinding and polishing machine made in accordance with the third form of this invention, the bowl being partly broken away to expose its working parts.

Fig. 8 is a top view, partly in section, looking in the direction of arrows 8, 8 of Fig. 7.

Fig. 9 is a fragmentary top view, partly in section, of the s'tylus holdin'g means.

Referring now to the first four figures of the drawing,

A it will be seen that lens grinding ,and polishing machine 10, made in accordance with one form of this invention, may be mounted on a table top 12 or any other suitable support. The machine includes a stand 14 which is mounted on the table and it will be noted'that said stand supports the'stylus-h'olding and pressing means. More specifically, it will be seen that stand 14 is bifurcated at 7 its upper end to accommodate a bifurcated horizontal arm 16 which is pivoted on shaft 18. The shaft is movable longitudinally of itself and hence transversely of the machine as a whole. At the forward'end of horizontal arm 16 is a second arm 20 which is clamped to the first arm by means of clamp 22. When clamp 22 is loose,

V 7 second arm 20 is free to pivot either leftwardly or right wardly, as desired or as required. When clamp 22 is tight against the two arms, the second arm is locked against movement relative to the first arm. A collet or chuck 24 is mounted on the second arm 20 and stylus holder 26 is held in said collet or chuck. A hole is formed in the stylus holder to accommodate the stylus 28 and said stylus holder is split and provided with a clamping screw 30 so as to'clamp the stylus in place.

The stylus holder 26 is rotatable in the collet or chuck and a. clamp member 32 is provided with said collet or chuck to lock the stylus holder against rotation therein.

Clamping member 22 is recessed at 22a to receive a second stylus 34. This second stylus projects upwardly work holder, as will hereafter more fully appear. A spring 44' is attached at one end to a rear extension 46 of arm 36 and it is attached at its opposite end to a stud 48 on extension 38 of stand 14.. This tends to support the weight of arm 36 and it also tends to swing it upwardly in clockwise direction as viewed in Fig. 1. To prevent such clockwise movement and to fix the posi tion of said arm 36, ratchet teeth 50 are provided'on 7 extension 38. and a pawl 52 engageable therewith is mounted on a trigger. 54 which is pivotallysupported on arm 36. A compression spring 56 acts against the trigger and causes it to hold pawl 52 firmly in engagement with ratchet teeth 50. It will be noted that the trigger is pivoted on pin 58 and the pawl is pivoted on pin 60. 'Pins'62 and 64 serve as guides for the pawl and prevent vertical displacement thereof. When the pawl is' 'in engagement with the ratchet teeth, arm 36 is locked against clockwise movement. The angular position of arm 36 may be adjusted by selective engagement of the pawl with the several ratchet teeth.

When the stylus 28 rests upon the work holder, as

, shown in Fig. 1, the work holder will serve as a support for the stylus and it will prevent arms 16 and 20 from dropping in counter-clockwise direction. When, however, the work holder is removed from the machine, it is important that'provision be made for an auxiliary supbowl, including the work holder 102. More specifically,

.vided to support arms 16,and 20when the work holder isremoved. This wire is secured at its lower end by means of screw or pin 68 to an ear 70 'on arm 16. The

.upper end of the wire extends through a hole in arm 36 and a thumb-screw 72 is provided to engage the wire and that this number 66 may be made of other material than wire, a length of cord or a flexible cable being quite satisfactory for this purpose.

Supported by stand 14 isla vertical shaft 74 which is V properlyjournaled for rotation on its vertical, longitudinal axis. The lower end of the shaft has a pulley 76 mounted thereon and said pulley is connected by means of a belt 78 to a second pulley 80. Pulley 80 is secured to a vertical shaft 82 which is properly journaled in bearing 84 for rotation on its vertical, longitudinal axis. A pulley 86 is also secured to shaft 82 and a belt 88 connects said pulley to a fourth pulley 90 which is mounted on the shaft of motor 92. It will be understood that the motor drives shaft 74 through the four pulleys and two belts and shaft 82 last above mentioned;

At the top of shaft 74 is an eccentric 94. This eccentric is. adjustable relative to the longitudinal axis of shaft 74 and a set screw 96'is provided for locking said eccentric in any selected position relative to said axis. Naturally, the distance of the eccentric from the axial center of shaft 74 will determine the extent of travel of said eccentric. It will be noted inFig. 3 that eccentric 94 projects up through the bifurcated end of arm 16. As

shaft 74 rotates, the eccentric acts upon said bifurcated arm 16 and causes it to move sidewardly in both direc" tions along the axis of shaft 18. This produces one of the movements to which reference has above been made,

namely the leftward and rightward movement. of the work holder and work, as will more clearly hereafter appear.

I Shaft 82 supports bowl 96, tool 98 and work 100 and it also supports the rest of the mechanism within the a flangedcollar or ring 104 is secured to shaft 82 and said collar or ring is mounted in a correspondingly shaped stood that this is but one means of holding the tool in' place. Mounting 112' is also removably secured to shaft '118 and a set screw 122 is provided to aifix said mounting'to said shaft.

A pair of pins 124 and 126 respectively are supported by ears 114 and 116 and these two pins support a pair of brackets 128 and 130. These brackets are joined by rings 132 and 134 respectively. Supported by brackets 128 and are two pairs of parallel uprights 136 .and

It will be understood that these upa 138 respectively. rights serve as vertical guide posts for the two horizontal rods 140 and 1420f the work holder 102. It will be understood from the foregoing that the uprights are adapted to move in two ways: they rotate or rather revolve about the axis of shaft 82 and they also engage i in pivotal movement about the axes of pins 124 and 126.

and the two rods which project sidewardly therefrom in i opposite directions are aligned on a common axis. -These rods project between the uprights andare movable longitudinally of themselves between said uprights. Hence the work holder is movable in three respects: it rotates with the uprights, it engages in pivotal movement with the uprights and it also moves axially of its two rods through or between said uprights.

It will be noted' in Fig. 4 that a recess 144 is formed; As'Fig. 3 clearly' in the top of the work holder 102. shows, stylus 28 projects into said recess and spring 42 acting through stylus '34 serves to apply whatever pressure may be necessary to hold the work in frictional en- 1 'gagement with the tool. Since stylus 28 is ofl? center relative to the axial center of shaft 82, it will be apparent 7 that when said shaft rotates, relative movement between the work holder and work on the one hand and the tool on the other hand will take place. It is this relative movement which provides the necessary abrasive or polishing action to grind or polish the lens.

A liquid 146 is contained in bowl 96 and it will be understood that said liquid includes whatever abrasive or polishing agent is conventionally used in operations of this kind. As the bowl rotates on shaft 82, the liquid tends to rotate with it and to flow up the side wall of the bowl to a certain height. A scoop 148 at the end of a tube 150 is supported by a bracket 152 in such position that it intercepts or catches the liquid and channels it up through said tube and against the work and tool. A steady supply of abrasive or polishing liquid is thereby directed upon the frictionally engaging faces of the tool and the work.

Referring now to Figs. 5 and 6 of the drawing, it will be understood that all of the apparatus which is mounted within the bowl, and also the bowl itself and the means for causing it to rotate are retained intact for the purposes of the modified form of the invention shown in said Figs. 5 and 6. This is a simplified version of the invention and it omits all of the complicated spring and adjustment mechanism shown in Fig. 1 for applying pressure through the stylus 28 upon the work holder. Stand 160 corresponds to stand 14 of the first form of this invention but it does not possess an extension piece corresponding to extension 38 shown in Fig. 1. Stand 169 is bifurcated at its upper end to receive rocker 162 which is mounted on a shaft 164. Shaft 164 projects through aligned holes in the upper, bifurcated end of stand 160. Shaft 164 is free to rotate in said holes and also to move axially of itself in either lateral direction. Rocker 162 is itself bifurcated to receive eccentric 166 which is adjustably mounted in channel 168 provided at the top end of vertical shaft 170. This shaft is journaled within a housing 172 and it is driven by the same means which drives shaft 74 above mentioned. As shaft 170 rotates, the eccentric acts upon the bifurcated rocker 162 and causes it to more leftwardly and rightwardly along the axis of shaft 164.

Projecting forwardly from rocker 162 is an arm or rod 174 which carries a stylus holder 176. This stylus holder is adjustably mounted on rod 174 and it may be moved both axially and angularly of said rod. A set screw 178 is provided to fix the stylus holder on the rod in any selected position thereon. It will of course be understood that other clamping means may be provided for the same purpose. A hole is formed in stylus holder 176 to accommodate the stylus 180 and a set screw 182 is provided to engage the stylus and fix it in place in said holder. Between the adjustment of the stylus holder on rod 174 and the adjustment of the stylus in said stylus holder, the point of the stylus may be placed in every conceivable position required for the proper operation of the machine.

The present form of the invention differs also from the first described form in that a weight 184 is provided for applying the necessary pressure to the work holder. The weight shown in the drawing is purely illustrative insofar as size and shape and method of application to rod 174 are concerned. It is slidably mounted on rod 174 for movement longitudinally thereof and a set screw 186 or other clamping means is provided to fix the position of said weight on said rod. Obviously, the same weight will apply different pressures depending upon its distance from the axial center of shaft 164. Both the stylus holder 176 and weight 184 are removable from rod 174.

There are times when it is desired to remove the stylus from the Work holder without disturbing the general set-up of the machine. This can be done in the present form of the invention by simply swinging rod 174 and everything that is connected to it in counterclockwise direction as indicated by the curved arrow in Fig. 5. A pin 6 188 in rocker 162 engages stand when rod 174 is elevated to a substantially vertical position so as to prevent it from falling over to the back of the machine.

Figs. 7, 8 and 9 show a third form of the invention. Stand 190 corresponds to stand 166 and rocker 192 corresponds to rocker 162 and shaft 194 corresponds to shaft 164. Eccentric 196, like eccentric 166, projects upwardly through the bifurcated end of the rocker. However, a beveled washer 198 is mounted on eccentric 196 and a pin 200 prevents upward displacement of said Washer. Rocker 192 has a complementary bevel 202 against which the bevel of the washer rests. The washer has two downwardly extending tongues 204 and 206 respectively which project into the bifurcated end of the rocker to prevent angular movement of said washer relative to said rocker. As the eccentric revolves about the axis of shaft 208, the beveled washer is caused to move toward and away from the axis of shaft 194 and consequently said washer is caused to ride up and down the bevel of said rocker. This has the eifect of causing the rocker to rock.

The forward end of rocker 192 is also bifurcated to accommodate a block 210. This block is pivotally mounted on a pair of set screws 212 and 214 which serve as trunnions relative thereto. A longitudinal opening is formed in block 210 to accommodate a bifurcated bar 216. This bar is movable longitudinally of itself through block 210 and a set screw 218 is provided to lock said bar in place. Stylus 220 projects through the bifurcated end of bar 216 and a weight 222 is mounted on said stylus. The weight rests against the bifurcated end of bar 216 and bears downupon it and upon the stylus. The stylus is adjustable longitudinally of itself through the weight and the bifurcated bar and it is also adjustable longitudinally of the bar through its slot 224 which is formed at its bifurcated end. The bar itself is adjustable both longitudinally and angularly of itself relative to block 210. Hence the point of the stylus may be placed in any desired location.

The bowl 226 and all of the mechanism mounted within the bowl, as shown in Fig. 7, are as described in connection with the first form of the invention. It will be noted in Fig. 7 that when rocker 192 is caused to rock in clockwise direction, the stylus-supporting bar 216 is caused to rock in counter-clockwise direction and the stylus is thereby thrust forwardly or rightwardly as viewed in Fig. 7. See the interrupted lines 228, 230 and 232. Conversely, when rocker 192 is caused to rock in counterclockwise direction (see dotted lines 234) rocker 216 rocks in clockwise direction and the stylus is pulled inwardly or leftwardly as viewed in Fig. 7. See interrupted lines 236 and 238. This rocking motion of the stylus is the fourth type of motion which the present machine is capable of, as has above been indicated.

It will be understood that the foregoing is descriptive of three forms of this invention. Modifications of these three forms, as well as other forms, may be had within the broad principles of the invention and the broad scope of the claim.

I claim:

A lens grinding and polishing machine, comprising a base, a tool rotatably mounted on said base for rotation about a vertical axis, motor driven means connected to said rotatably mounted tool and causing it to rotate about its said vertical axis, a lens holder positioned above said tool for holding a lens in contact with said tool, a pair of guide members pivotally connected to said tool on diametrically opposite sides thereof for pivotal movement about a horizontal axis, said guide members being movable with said tool about its vertical axis of rotation, means connecting said lens holder with said guide memhers to cause said lens holder to engage in rotary movement with said tool and in pivotal movement with said guide members, said lens holder being free to move relative to the guide members on a line parallel to the pivotal axis of said guide members, a frame extending upwardly from said base, an arm mounted intermediate its endslon said frame for pivotal movement about a horizontal axis extending transversely of said arm and for lateral movement in both directions along said last mentioned horizontal axis, a stylus pivotally mounted on one end of said arm for pivotal movement about a horizontal axiswhich is parallel to the last mentioned hori- V zontal axis, said stylus being situated on said arm for engagement with the lens holder, pressure means con- 7 'nected to said stylus and causing it to bear down upon the lens holder and thereby to cause the lens held by said lens holder to bear down upon the tool, and motor V driven means connected to the opposite end of said arm and causing it to move laterally along and pivotally' about its said horizontal axis, whereby the stylus is caused to rock about its horizontal axis and to move laterallywith said arm, said opposite end of the arm being bifurcated and the motor driven means which causes said arm to "move along and about its said horizontal axis including an eccentricwhich engages said bifurcated end-70f the arm and engages in movement of revolution about a vertical axis, said bifurcated end of the arm having a sloping portion and said eccentric having a member which engages higher and lower parts of said sloping portion, as the eccentric revolves, thereby causing said arm to rock about its said horizontal axis and causing said stylus to rock about its own horizontal axis.

References Cited in the file of this patent UNITED STATES PATENTS Doddu July 1, 1941 

